The Acoustic Impedance node adds a boundary condition defining a relation between the local acoustic pressure
p and the normal acoustic velocity
n·u, that is, the acoustic impedance Z. The condition specifies the inward normal velocity
Note that this condition is not equivalent to the general impedance condition, as given by Myers (see Ref. 4), when a flow is present. This means that, for example, it cannot be used at a reacting surface which has a tangential flow. For this kind of detailed conditions a frequency domain representation is needed.
Enter a value or expression for the Acoustic Impedance Z (SI unit: Pa·s/m). The default expression is
cwe.c0*cwe.rho0 which is the characteristic specific impedance
ρ0c
0 of a propagating plane wave.